Some Fish Are Still Full of Mercury, for a Worrying Reason

Environmental success stories are seemingly in short supply, but the fall of mercury is one of them. Released by coal-burning power plants and other industries, mercury—a toxic metal—circulates in the atmosphere, enters the ocean, worms up the food web and, via the seafood we eat, ends up in our bodies. For decades mercury in seafood has been a health scourge, because it inflicts long-term harm on the brain and increases the risk of heart disease. It’s especially risky for developing fetuses, and mothers-to-be have long been warned away from mercury-rich tuna and swordfish.

But from 1995 to 2010, mercury concentrations in the Northern Hemisphere fell by 30 percent, , falling coal use, and phaseouts of mercury in commercial goods. And in 2017, the came into force.